Brake slack adjusting mechanism



Nov. 4, 1952 Filed Feb. 4, 1947 Nov. 4, 1952 Filed Feb. 4. 1947 BRAKE T.JAMES, JR 2,616,527

SLACK ADJUSTING MECHANISM 4 Sheets-Sheet 2 Figs Nov. 4, 1952 T. JAMES,JR 2,616,527

BRAKE sLAcK ADJUSTING MECHANISM Filed Feb. 4, 1947 4 sheets-sheet 3 Fly.5

Attorney.

Nov. 4, 1952 T. JAMES, JR 2,616,527

y BRAKE SLACK ADJUSTING MECHANISM Filed Feb. 4, 1947 4 Sheets-Sheet 4Patented Nov. 4, 1952 BRAKE SLACK ADJUSTING MECHANISM Thomas James, Jr.,Oaklyn, N. J., assignor to Specialty Brake Appliance Company, Camden, N.J., a corporation of N ew'J ersey Application February 4, 1947 SerialNo. 726,284

(Cl. 18S-198) 12 Claims.

This invention relates to brake slack adjusting mechanisms, and moreparticularly to brake slack adjusting mechanisms for the wheel brakesemployed on railroad vehicles.

lt is an object of the `invention to provide unitary slack ladjustingmeans mounted in one of the brake levers of a brake mechanism which isadapted for both power and manual operation.

A more specific object is te provide in an air brake mechanism forrailway vehicles, comprising a pair of oppositely disposed brake leversand pull rod means connecting said levers, an automatic, unitary slackadjusting means mounted in one of said levers and operable on said pullrod means to take up slack in the said brake mechanism due to wear onthe parts.

A still further object is to provide in brake mechanisms of the classdescribed electrically operable slack adjusting means including areversible electric motor, automatically operable power-controlling unitVsuch as a switch mechanisrn for causing operation of said motor whenslack occurs in said brake mechanisms to take up such slack, andmanually operable switch means for reversing the operation of said motorto cause separation or the parts and thereby enable disassembly andrepair of the brake mechamsm.

In carrying out theinvention in one form thereof, there is providedslack adjusting means for the brake system of a railroad car whichincludes a power source separate from the power source oi the brakesystem. This power source is mechanically connected to the linkage ofthe brake system. and is arranged for actuation to take up the slack insaid linkage by varying the relative positions of the parts thereof whenthe brake shoe is fully applied to the wheel. A control systern forautomatically actuating the slack adjusting power source is arranged tobe operated by movement of an element of the. linkage to Aand beyond apredetermined position when the brake shoe is applied to the wheel.Further in accordance with the invention, the slack adjusting powersource is a reversible elect-ric motor carried by one ci the operatinglevers of Athe wheel brake mechanism. The motor is connected to `apairci spaced pinions arranged to engage a plurality of spaced pins forminga self-cleaning rack mounted in a pair of spaced, substantiallyparallel, pull rods.

Other and further objects will become apparent as the description of theinvention progresses.

Of the drawings:

Fig. 1 is a side elevational view ofv a brake mechanism showing thepreferred form of slack adjusting means associated therewith.

Fig. 2 is an end View, partly in section, taken substantially along line2-2 of Fig. l.

Fig. 3.is a Afragmentary end View, partly in section, takensubstantially along line 3 3 of Fig. 1.

Fig. 4 is a side elevational View, partly in section, of the switchmechanism for the slack adjusting means, together with .a wiring diagramof the electric circuit, including the electric motor, the source ofelectric potential, and the associated control and reversing switches.

Fig. 5 is a fragmentary elevational view of a portion of the structureshown in Fig. 3, certain parts being shown removed or broken away tomore clearly illustrate the arrangement of the gearing;

Fig. 6 is a view of the slack adjusting mechanisrn, partly in section,taken substantially along line E-G of Fig. 5.

Fig'. 7 is a View of the slack adjusting mechanism, partly in section,taken substantially along line 1 1 of Fig. 5; and

Fig. 8 is a side elevational view of a brake mechanism and associatedbrake slack adjusting means oi a modified construction.

Referring to the drawings and more particularly to Figs. 1 to 3 thereof,the numeral l indicates generally the combined assembled deviceconsisting of a brake mechanism indicated generally at 2 and the slackadjusting means for said brake mechanism indicated generally at 3.

The brake mechaism 2, manually controllable, comprises a supportingframe 4 which, when the ldevice is employed on railroad Vehicles, may bethe wheel truck upon which the vehicle body proper is mounted. A wheel5, with which the brake mechanism 2 is associated, is rotatablysupported in the usual manner on frame ll. Brake elements includingshoes t and l, mounted in any suitable manner in brake heads 8 and 9respectively, engage the periphery of wheel 5 at opposite sides thereof.Brake head B is supported upon a pin l which extends through alignedapertures provided in a substantially vertically 4disposed brakeoperating lever i2 intermediate the ends of the latter, the lower endsof a pair of substantially Vertical supporting arms i3 and I4, and inthe outer reduced portion l5 of the said brake head 8. rEhe reducedportion of brake head 8 is bifurcated, as shown in Figs. 1 and 2, so asto receive a portion of lever l2. The upper ends of arms I3 and ill arerotatably supported on pins Il and I6 respectively, which in turn aresecured-in any suitable mannerto the supporting frame-ll. Lever I2 andbrake shoe 6 thus are effectively supported by arms I3 and I4.

Brake head 9 for brake shoe l is also bifurcated, as shown at I8, so asto receive the inner extended portion I9 of a substantially verticaldead lever 20. Brake head 9 is pivotally mounted on a pin 23 extendingthrough aligned apertures provided in level` and the bifurcations I8 ofsaid brake head 9. The upper end of lever 20 is pivotally supported on apin 24, which in turn is secured in any suitable manner to the frame 4.The lower ends of levers I2 and 20, as will appear more fuilyhereinafter, are connected by a pair of adjustable means, links 25 and25, commonly known as pull rods, so that upon movement of lever I2 byoperating mechanism 21 attached thereto the brake shoes 5 and 'I aresubstantially simultaneously moved against or out of engagement withwheel 5.

The operating mechanism 21 may be of any suitable type, and as hereinshown is a power source which comprises a reciprocating air motor 28known as a brake cylinder. The casing 29 of brake cylinder 28 is securedto frame 4 by any suitable means. The piston rod 30 of brake cylinder 28has an enlarged collar 33 secured to the outer end thereof by means of alocking pin 34. A push rod is connected at one end to the hollowinterior of piston rod 30 by any suitable means. The outer bifurcatedend 35 of push rod 35 is connected by means of a pin 31 to the upper endof lever I2. Thus upon operation of lever i2 to the right (Fig. 1) bybrake cylinder 28 and movement of the mechanical linkages, the brakeshoes 5 and 'I will be applied to wheel 5, as shown in Fig. l; and uponoperation of lever I2 to the left, as by selective operation of manuallycontrollable means for power source 2`| located in the engine to whichthe railroad car is connected, brake shoes 6 and 'I are moved out ofengagement with said wheel. The brake mechanism thus far described,excepting the parts modified in accordance with the invention asdescribed hereinafter, is generally old in the art and was describedmore or less in detail so as to enable a better understanding of thebrake slack adjusting means which comprises the present invention.

The present invention contemplates mechanism which functionsautomatically to take up slack in the brake mechanism as soon as itoccurs therein. Efficient operation of the brake mechanism, therefore,is assured at all times, and as will appear more fully hereinafter thepredetermined travel of the actuating element, the piston of brakecylinder 28, is maintained.

Referring more particularly to Figs. 1, 3, 5, 6 and '7, the lower end ofdead lever 20 has provided thereon an enlarged hollow portion or casing38 for housing another power source, the electric motor 39, andreduction gearing 40 of the brake slack adjusting means 3-. Casing 38comprises a partially convex inner wall 43, relatively fiat side walls44 and 45, a at top wall 46, a partially convex bottom wall 4l, and afiat outer wall 48. The outer wall 48 is provided with a relativelylarge rectangular opening 49, which is normally closed by a cover plate50. Cover plate 50 is attached to outer wall 48 in any suitable manner,such as by bolts 53.

As shown more particularly in Figs. 5 and 7, motor 39 has provided nearthe outer end thereof a depending supporting member 55 which seats upona support 54, secured to and extending upwardly from the bottom wall 4lof casing 38. Bolts 5B extending through aligned threaded openingsprovided in support 54 and supporting member 55 rigidly secure the motor39 in the position shown in Fig. 7. An opening 51 is provided in theconvex portion of bottom wall 4'! near the outer end thereof so thataccess may be had to bolts 55.

rIhe armature shaft 58 of motor 39 has secured thereto a pinion 59 whichmeshes with a relatively large gear keyed to a shaft 5|. Shaft 6| isjournalled at one end in a bearing 53 provided in cover plate 59 and atthe other end in a bearingI 64 provided in an intermediate supportingmember 65 secured to and depending from top wall 45. As shown moreparticularly in Figs. 5 and 6, the outer end of shaft 5| has formedthereon a square portion 66 which enables attachment thereto of a wrenchso that the gears may be operated manually if it is so desired. Anenlarged recess 0l is provided in cover plate 50 around the outer end ofshaft 5I to facilitate the attachment of a wrench to said shaft. A smallgear 58 is secured to shaft 5| which meshes with a larger gear 09secured to the outer end of a shaft l0. Shaft 'it extends throughsupporting member 55 and is journalled intermediate its ends in abearing 'II provided in said supporting member. The other end of shaft'I0 is journalled in a bearing 'I2 provided in a boss I3 secured to andextending inwardly from wall 43. The square end 55 of shaft 5| iscovered by a small cover plate 'I4 which is secured to main cover plate50 by screw bolts l5. A worm 'i5 is secured to shaft 'I0 intermediatethe ends of the latter, which meshes with a worm wheel 'I'I keyed orotherwise secured to a shaft 18. Shaft 'I8 extends through and ismounted in any suitable bearings 'I9 and 80 provided in side walls 44and 45 of casingI 38.

A collar 83, secured to shaft 'I0 by a set screw 84, extends between theleft hand end (Fig. 6) of worm 'i6 and the inner surface 85 of boss 73.The outer surface 86 of the right hand end (Fig. 6) of worm 'I6 lies insubstantially abutting relation with the outer surface 87 of a boss 88provided at the lower end of supporting member 65.

As shown more particularly in Fig. 5, worm wheel 'I'I is held againstaxial movement to the left by a collar 89 secured to shaft 75 by a setscrew 90. The right hand side (Fig. 5) of worm wheel 'I'I is providedwith a hub portion 93, the outer surface 94 of which lies insubstantially abutting relation with the inner surface 95 of a boss 96extending inwardly from side wall 45 of casing 38. Axial movement ofworm wheel 1l along shaft 'I8 to the right accordingly is alsoprevented.

Shaft '18, it will be observed, extends beyond the outer sides of sidewalls 44 and 45 of casing 38. One end 91 of shaft 18, in assembly,extends through laterally aligned elongated slots 98 and 99 providedrespectively in the laterally spaced members |02 and 03 of pull rod 25.Member |02 is relatively flat and extends the entire length and formsthe basic element of pull rod 25. The other end of member |02 isprovided with an enlarged apertured portion |94 for receiving a pin |05which, as will appear more fully hereinafter, forms the operatingconnection between lever I2 and pull rods 25 and 26. Member |03, on theother hand, extends over only a portion of the length of pull rod 25 andthe upper end thereof is bent inwardly, as shown at |06, and overliesthe upperl edge |01 of member |02. Members |02 and |03 may be securedtogether in any suitable manner, such as by welding.

Members |02 and |103 orpullrcd A25 vhave provided near the lower edgesthereof za series vof laterally aligned apertures `for receiving `respectively the reduced ends |08 `'and v|09 of a series of'spaced pins |I0.Pins l|10 lformurself-cleaning rack over a portion of the length of pulll-rod 25 which meshes with a pinion H3 secured on the end portion `91 of`shaft 18.

Pull rod 26 is similar vin construction to pull rod 25 and alsocomprises a fla-t Vmember `||4 extending over the entire length thereofand la relatively short member H5. The upper portion of member 5 is bentinwardly, as Yshown at 'II-6 in Fig. 3, and overlies the upped'edge||1fof member H4. Members H4 and I1'51aresecured together by welding orby any other lsuitable means and also have provided 'therein 'laterallyaligned elongated vslots H8 and H9 respectively for recel-ving the otherend of shaft 18. Laterally'aligned apertures are provided in members|'I-4 and H5 for receiving the reduced ends |21 and |22 respectively ofa series of spaced lpins |23. Pins |23, like the pins I`I0, `form laself-cleaning rack which meshes with a pinion |24 secured `to the end|20 of shaft 18.

The other end of member I4 is provided with an enlarged aperturedportion |25 throughwhich the pin |05 extends. As shown 'in Fig. 2'p'in1| 015 also extends through an aperture provided vat the lower end oflever |2. [In order v'to hold V*lever "I2 in centered position, sleeves|26 and |21 are provided on pin |05 which extend 'between lever I2 andenlarged portions |04 and |25 respectively of pull rods 25 and 26.

Slots 98, 99 and H8, H9 respectively extend tothe extreme right hand-ends (Fig. l) of -pull rods 25 and 26. Thus to assemble Ythe parts, theouter ends of slots 98, 99 and I I8, `I I'B'are brought into alignment`respectively Vwith the `cuter ends 91 and |20 of shaft 18. Lever v20 isthen moved to the left ('Fig. l), causing the pinions H3 and |24 to rollover pins H0 and |23 in meshing relation therewith.

In order to prevent accidental disengagement of pinions I I3 and |24with pins I I0 and |23'stop members |28 are provided near the right handends (Fig. l) of pull rods 25 and 26. Stop meinbers |28 may be oi anysuitable construction, and, as herein shown, each of said memberscomprises a bolt |29 or T-shaped construction, "the rectangular headportion v| 30 thereof extending Yinto correspondingly shaped recesses|33 `provided the lower edges of members |02, |03 and -|I4, H5 of pullrods 25 and 26 respectively. The -upper threaded ends of bolts |29extend through apertures provided lin the upper portions |06 and ||6 ofmembers |03 and I I5 Vand ,nuts |34 retain'the bolts in position. Bolts|29 `also have provided thereon protective sleeves |35, as shown in Fig.'1.

From the foregoing description it is seen that upon rotation of motor 39in one direction pinions H3 and |24 operating on pins H0 and |23 willmove levers I2 and 20 toward each other, thereby taking up any slackthat 4may occur inthe brake mechanism 2., When motor 3'9 is reversed,levers I2 and 20 will be moved :away from each other, thereby creatingsuiiicient slack to yenable replacement or the "brake shoes 6 and 1.'.For removal of wheels 5, the stops |128 and 4pin- |05 are removed andpull rods 25 and 26 may then be disengaged from levers I2 and20. I s

The operation of electric motor y-39 is controlled by apower-controlling unit such as `the :switch mechanism -shown r-more'-particularly in Figs. 1 and 4 and indicated Agenerally 'by the numeral|40. As shown inFigs. 5, S'and'f', the upper wall 46 of casing 38 hasprovided near lthe outer side thereof araised portion |42 forming asubstantially rectangular chamber |43. A reduced rectangular opening |44is provided in wall 4E which connects chamber |43 with the interior :ofcasing 38 immediately above velectric vmotor 39. The reduced opening |44provides a pairof spaced shoulders |45 and |46. A plate |41 constructedof electric insulating material and having spaced electric contactelements |48, |489, |49 and |49u mounted therein seats upon shoulders|45 and |46. Electric mo-tor 39 also has mounted thereon a plate |50constructed of electric insulating material and having spaced electricconductor bars |52, |529, |53 and |53ab vmounted therein. Conductor bars|52 and |52 are connected respectively to the opposite ends of the iieldcoil L| 54 of motor 39, while bars |53 and |53a are connectedrespectively to the "opposite sides of the armature |55, as shown moreparticularly in Fig. 4. As shown in Figs. l5 and 7 electric conductors|56, 156e, '|51 and |519 connect contact elements 48, |48, |49 and 149erespectively with conductor bars |52, |529, |53 and |53a. Electric motor39 may be of any suitable type, but for the purpose of illustration itis shown herein, particularly in Fig. 4. as being of the direct Icurrentseries time.

Conductors |60, |60, |6-I and Itla are connected at one end thereof tocontact elements |48, |489, |49 and |49a respectively and may be coveredwith any suitable insulating material. Lever 20 has provided vtherein alongitudinally extending passage |58 Vthrough which conductors |60,|6021, |6| and |61a extend. Conductor |6Ia -connects contact element|49avwith `the extension |65 of a contact arm |66 of control switch |40.Contact arm |66 is pivotally mounted on an insulated support |61 securedto and extending inwardly of side 'wall |68 of the casing |64 of control-switch |4`0 and is `provided With an arcuate contact surface |69 whichengages the outer periphery of an -annular contact element |10. A coilspring I1| connected at one end to an insulated stud |12 provided on arm|66 and at the other end to a stud |12' secured to and extendinginwardly from side wall v|68 vresilie ently holds the` said arm |66 incontact with annular contact element |10. Contact element |10 isconnected to a vertical arm |13 by a disc |14 constructed of insulatingmaterial. Arm |13 and annular contact element |10 are rotatably mountedon a stud |15 having a ring |16 of insulating material provided thereon,the said stud being secured in any suitable manner to side wall |60 ofcasing |40.

Annular contact element |10 has secured thereto a Acontact member |11which is adapted to engage the upper end |18 of a contact arm |19, thelower end of the latter being pivoted, as shown :at |80, to the upperend of a, bracket |82 constructed of material which is a good conductorof electricity. Bracket |82 is secured by bolts |83' to a plate |64'constructed of insulating material which in turn is secured in anysuitable manner to the bottom wall |85 of casing |64.

Contact arm |19 has secured thereto and extendingA laterally thereof astud |86 having a ring |81 of insulating material thereon which receivesthe inner apertured end |88 of the inner ele ment .|92 of an adjustablelink |80. A disc |90 of insulating material also extends between arm |19and inner element |92. The inner element "|192 of link |89 is providedwith an :in-

ternally threaded bore |93 in which extends the correspondingly threadedend |94 of outer element |95 of said link. Outer element |95 extendsthrough the end wall |96 of casing |64 and lock nuts |91 and |98provided on said element at opposite sides of the wall |96 effectivelyhold the parts in adjusted position. A protective cap |99 is provided onthe outer end of element |95, as shown in Fig. 4. Thus by rotating outerelement |05, contact arm |19 may -be moved toward or away from contactmember |11.

As shown in Fig. 4, a conductor 200 connects bracket |82 with a pole |62of a reversing switch |63 mounted within the casing |64 of controlswitch |40. A second pole 202 of switch |63 is connected by a conductor202' with a third pole 203 of said switch. A fourth pole 204 of switch|63 is connected by a conductor 204 to pole |62. Switch |63 alsocomprises a switch member 205 constructed of insulating material havinga pair of spaced conducting contact elements 206 and 201 mounted thereinwhich, when in the position shown in Fig. 4, engage respectively poles|62 and 262, but when actuated by a push-button, as will presentlyappear, are 'adapted to engage poles 203 and 204 respectively. Anactuating rod 203 is secured to switch member 205 and extends through anopening provided in wall 2|0 of the casing 2|3 of switch 63. R/od 29Shas secured to the outer end thereof a head or button 2|4. A coil spring2|5 extends betwecn button 2|4 and the wall 2|0 and normally retains thecontact elements 206 and 201 in contact with poles |62 and 202. Uponactuation of rod 208 inwardly, contact elements 206 and 201 are broughtrespectively int-o engagement with poles 203 and 204, thereby, as willpresently appear, effecting a reversal of motor 39. Upon release ofbutton 2|4, spring 2|5 restores the parts to the position s-hown in Fig.4 wherein contact elements 206 and 201 again engage poles |62 and 292respectively.

Conductor |6| connects contact element |49 with pole 202 of switch |63.Conductor |60a connects contact element |48a with the contact element201 of switch |63, while conductor |60 connects contact element |48 withthe pole 2|9a of a line switch 2| 9. Contact element 203 of switch |63is connected to a second pole 2|9b of line switch 2|9 by a conductor209. Poles 2|9HL and 2|9b may be connected by switch 2|9 to any suitablesource of electric potential, such as a battery 2|6, by conductors 2|1and 2|8 respectively.

As shown in Figs. 1 and 4, the collar 33 secured to the piston rod 30 ofbrake cylinder 28 has secured to and depending therefrom =a plate 220which is adapted to engage the upper antifriction end 222 of contact arm|13. A resilient means, coil spring 223, secured at one end to arm |13and at the other end to a bracket 224 secured to and extending upwardlyfrom casing |64 urges arm |13 to the right, tending to establish contactbetween the upper end |18 of arm |19 and contact member |11. Normally,arm |13 is so held by plate 220 that contact is broken between contactmember 11 and arm |19. However, when slack occurs due to wear on theparts of the brake mechanism, piston -rod 30 and plate 220 are moved tothe right (Figs. 1 and 4) a greater than normal distance, causing spring223 to swing arm |13 a greater than normal distance in a clockwisedirection (Figs. 1 and 4), thus bringing contact member |11 intoengagement with arm |19 and thereby completing the circuit to electricmotor 39, which then operates to take up such slack. Fig. 4 shows theplate 220 attached to the collar 33 of piston rod 30 out of engagementwith arm |13 and switch elements |11 and |19 in contact with each other.The circuit to electric motor 39 is accordingly closed.

By virtue of suitable provisions or structure such as the annularcontact element |10, contact between it and arm |66 is always maintainedregardless of the arc through which arm |13 is swung by operation ofbrake cylinder 28.

When the slack has been taken up, piston rod 30 will have been moved tothe left (Figs. l and 4) a sufcient distance to cause plate 220 toactuate arm |13 to break the contact between contact member |11 and arm|19. The circuit to motor 39 is thus broken and it consequently comes torest.

From the foregoing description, the operation of my improved slackadjusting means is believed to be clear. However, in order to correlatethe various elements thereof a brief rsum of the operation of the deviceas a whole will now be given.

Contact arm |19 is first adjusted by manipulation of outer element oflink |89 until it assumes the proper position with respect to contactmember |11. The proper position under operating conditions is obtainedwhen contact member |11 and contact arm |19 are just out of contact witheach other at the time that brake cylinder 20 has operated piston rod 30and consequently arm |2 to the right, bringing shoes E and 1 intobraking contact with wheel 5. As a result of the broken contact betweencontact member |11 and arm |19, the circuit to motor 39 is interruptedand consequently the motor remains at rest. To release the brakes,piston rod 30 is moved to the left (Fig. 1), causing plate 226 to swinglever |13 against the action of spring 223 in a counter-clockwisedirection (Figs. l and 4). Such action, however, brings contact member|11 farther away from contact arm |10, since the latter is held rigidlyin adjusted position by link |69, and consequently contact betweenmember |11 and arm |19 remains broken. Now, when the brakes are againapplied, the piston rod 30 moves to the right carrying plate 220 with ituntil the predetermined extent of piston travel is reached. At this timethe brakes are fully applied. When piston rod 30 and plate 220 havereached the predetermined extent of travel, arm |13 still engages plate220 and consequently elements |11 and 19 are still out of engagementwith each other and the circuit to motor 39 remains broken. The brakemechanism now continues to function in a normal manner until slackoccurs therein due to wear on the brake shoes 6 or 1, or other parts ofthe mechanism. When such slack occurs, the piston and its rod 30 will bepermitted by such slack to move to the right beyond the predeterminedextent of piston travel aforesaid. When this extra movement takes place,spring 223 swings lever |13 in a clockwise direction, bringing contactmember |11 and arm |19 into contact with each other. Inasmuch as contactelements 206 and 201 of reversing switch |63 are in contact with poles|62 and 202 respectively, the circuit to the electric motor 39 isclosed. Current now ows from the battery 2|6, through conductor 2| 1,switch 2|9, pole 2|9a, conductor |60, field coil |54, conductor |60,contact element 201, pole 202, conductor 6|, armature |55, conductor|6|, contact arm |00, contact element |10, contact member 11, contactarm |19, bracket |82, conductor 200, pole |02, contact element 200,conductor 209, pole 2|9b, switch 2I9, and vconductorl 2 I8 and returnsto battery 2 I0.

Upon operation of actuator motor 39, pinions I3 and |23 will actuate therack members formed by pins and |23 respectively on pull rods 25 and 26,thereby shortening the length of the latter and causing movement oflevers 20 and I2 toward each other. When this occurs, lever I2 will beactuated slightly in a counter-clockwise direction about pin |0 (Fig. 1)as a pivot, actuating piston rod 30 and consequently plate 220 to theleft, thereby swinging arm |13 in a counter-clockwise direction to bringcontact member |11 and arm |19 out of contact with each other. When thisoccurs, the circuit to the motor is interrupted and the latter` comes torest. It, therefore, is seen that all slack in the brake mechanism v2 istaken up byl the shortening of the effective length of pull rods 25 and26, and the brake mechanism may 'now again function in a normal manneruntil slack again occurs therein. Piston rod 30 of brake cylinder 28 nowagain operates at its normal predetermined extent of travel asaforesaid. It is also seen that the mechanism just described :functionsto take up slack while the brakes are applied, and accordingly suchslack is eliminate as fast as it occurs in the brake mechanism. Whenslack again occurs in the mechanism the operation just described isrepeated and such slack is then again taken up. These operations arerepeated until the brake shoes, for example, have been worn to such anextent that replacement thereof appears desirable.

In order to make replacements and other repairs to the apparatus as awhole, the operator presses push-button 2| 4 of switch |63 inwardlyagainst the action of spring 2 I 5, bringing contact elements 208 and201 into contact with poles 203 and 204 respectively. He also adjustslink |89 to make contacty between switch elements |11 and |19. Currentnow ows from battery 2 I6 through conductor 2|1`, switch 2I9, pole 2I9a,conductor |00, field coil |54, conductor |505, contact element 2,01,pole 204, conductor 204', pole |02, 'conductor 200, bracket I 82,v arm|19, contact member |11, contact element |10, arm |09, conductor IEW,armature |55, conductor IGI, pole 202, conductor 202', pole 203, contactelement 200, conductor 209, pole 2I9b, switch 2|9, and conductor ZIB andreturns to batteryl 2||i.l The ycircuit to motor 39 is, accordingly,reversed whereupon pinions I|3 and |24 are actuated in la clockwisedirection, causing pull rods 25 and 2E to move levers |2 and 20 awayfrom each other. This movement of levers I2 and 20 and pull rods 25 and26 produces sufcient slack to permit replacement of 'brake shoes 9 and1.

When pull rods 25 and 2S have been lengthened sufficiently, the operatorreleases push-button 2|4, whereupon contact elements 206 and 201 areactuated into contact with poles |62 and 202 byy spring 2|5, thusreconditioning the circuit for normal operation. To readjust the brakesafter replacement of brake shoes 6 and 1, the brakes are simply appliedby operationv of brake cylinder 28 and the predetermined travel of thepiston and rod 30 thereof is reestablished.

`In the. event that it should for any reason be desired to manuallyoperate the slack adjust.- ing means, the brakes are first applied byoperation of' brake cylinder 28, Cover plate 14 is .1 as. in newinstallations.

I0 now removed and a wrench fastened to the square end 00 of shaft 6I.Upon operation of shaft 6| in this manner pinions ||3 and |24 areactuated to shorten pull rods 25 and 20 and thereby take up the slack inthe brake mechanism.

Upon operation of shaft 6| in the opposite direction, the length of pullrods 25 and 26 is increased. By removing stops |28 from pull rods 25 and26, the latter may be entirely separated from lever 20 by continuedmovement of shaft 6 as just described.

Due to the friction in the reduction gearing 40, it is apparent that thepull rods 25 and 29 will be effectively held in each position of ad-J'ustment and that the effective length thereof can be changed onlyv byoperation of said gearing either by electric motor 39 or by manualoperation of shaft 6I.

Fig. 8 illustrates a modification of the present invention wherein a.pair of cables 25 and 29 is provided instead of pull rods. As showntherein, the outer ends of shaft 18 have provided thereon sheaves 225and 220. One end of each of the cables 25' and 26' is anchored, as shownat 221, to the sheaves 225 and 229; while the other end is anchored, asshown at 29, to a pin |05' connected to the lower end of lever I2. Theother parts of the apparatus are identical with those shown in Figs. 1to '1. Accordingly, when slack occurs in the brake mechanism, sheaves225 and 220 will be operated in a clockwise direction to bring levers l2and 20 toward each other and thereby take up such slack. The brakemechanism then functions in a normal manner until slack again occurstherein when the operation is repeated.

In the event that it is desired to replace the brake shoes or to makeother adjustments, the associated electric motor is reversed, aspreviously described, causing the sheaves 225 and 226 to rotate in acounter-clockwise direction, thereby producing sufficient slack incables 25 and 26 to enable the levers I2 and 20 to be moved away fromeach other. The worn brake shoes may now be replaced with new ones. Whenit is desired to disassemble the apparatus, the anchoring mechanism 229may be disengaged. Levers I2 and 20 will then be disconnected and may bemanually moved away from wheel 5.

It, therefore, is seen that simplified and highly useful slack adjustingmechanisms have been provided which automatically take up the slack inbrakev mechanisms as soon as it occurs therein. The slack is taken upwhile the brakes are applied and therefore it is eliminated as fast asit occurs.. Efficient operation of the brake mechanisms is, therefore,assured. By providing automatic means of the character described fortaking up slack, constant inspection of the brake mechanism is.unnecessary. Brake shoes are so constructed as to provide efficientservice for long periods of time, and with automatic means for taking upslack in the system the mechanism as a Whole requires but littlepersonal attention.

The slack adjusting mechanism except the switch mechanism |40 is carriedentirely by one of the brake levers and therefore constitutes aself-sustained unitary structure. The slack adjusting mechanism may.therefore, be readily installed in. existing braker mechanisms as wellIn existing installalevers and the associated pull rods.

The invention, for the purpose of illustration, has been shown inconnection with brake mechanisms of the type having a brake shoe ateither side of a wheel. It is apparent, however, that the invention isequally well adapted for use with brake mechanisms having one brake shoeor more than two brake shoes as well.

It is apparent that the invention is also adapted for use in connectionwith brake mechanisms employing brake drums instead of wheels andwherein various types of brake shoes or bands are utilized in connectiontherewith. It is obvious that other modications may be made to thedevices herein shown and described without departing from the invention.

Accordingly, while the embodiments of the invention herein shown anddescribed are admirably adapted to fulfill the objects primarily stated,it is to be understood that it is not intended to limit the inventionthereto, since it may be embodied in other forms, all coming within thescope of the claims which follow.

What is claimed is:

1. In a device of the class described, the combination of a brakemechanism comprising a plurality of spaced brake elements, brake leversoperatively connected to said brake elements, adjustable pull rodsoperatively connecting said brake levers, reciprocable operating meansconnected to one of said brake levers for applying and releasing saidbrakes, slack adjusting means mounted on and housed within one of saidlevers comprising an electric motor, pinons operable by said motor, andreduction gearing connecting said motor to said pinions, rack meansprovided on said pull rods meshing with said pinions whereby uponoperation of said motor in one direction the effective length of saidpull rods is decreased, a control switch for said motor, means operatedby said operating means for holding said switch open only during normaltravel of said operating means in either direction, and automaticallyoperable means for closing said switch upon movement of said operatingmeans to and beyond its normal extent of if travel when applying thebrakes to thereby cause operation of said motor to shorten eifectivelysaid pull rods to take up the slack in said brake mechanism.

2. In a device of the class described, the combination of a brakemechanism comprising a pair of spaced brakes, a brake lever operativelyconnected to each of said brakes, adjustable pull rods operativelyconnecting said brake levers, reciprocable operating means connected toone of said brake levers for applying and releasing said brakes, slackadjusting means mounted on one of said levers comprising an electricmotor, pinions operable by said motor and reduction gearing connectingsaid motor to said pinions, rack means provided on said pull rodsmeshing with said pinions whereby upon operation of said motor in onedirection the effective length of said pull rods is decreased and uponoperation of said motor in the opposite direction the length of saidpull rods is increased, a normally open control switch for said motor,means operated by said operating means for holding said switch openduring normal travel of said operating means in either direction,automatically operable means for closing said switch upon movement ofsaid operating means beyond its normal extent of travel when applyingthe brakes to thereby cause operation of said motor to actuate said pullrods to take up the slack in said brake mechanism,

and a manually operable reversing switch for reversing the operation ofsaid motor.

3. In a device of the class described, the come bination of a brakemechanism comprising a pair of spaced brakes, a brake lever operativelyconnected to each of said brakes, adjustable pull rods operativelyconnecting said brake levers, reciprocable operating mechanismoperatively connected to one of said brake levers for applying andreleasing said brakes, slack adjusting means mounted on one of saidlevers comprising an electric motor, pinions operable by said motorthrough reduction gearing, racks on said pull rods meshing with saidpinions, whereby upon operation of said motor in one direction theeffective length of said pull rods is decreased and upon operation ofsaid motor in the opposite direction the length of said pull rods isincreased, a control switch for said motor, means operated by saidoperating mechanism for holding said control switch open only duringnormal travel of said operating mechanism in applying and releasing saidbrakes, resilient means for closing said switch upon movement of saidoperating mechanism beyond its normal extent of travel when applyingsaid brakes to thereby cause operation of said motor to shorten saidpull rods to take up the slack in said brake mechanism, said shortenedpull rods so actuating said brake levers as to limit the movement ofsaid operating mechanism to its normal extent of movement.

4. In a device of the class described, the combination of a frictionbrake mechanism, operating means including an actuating element for saidbrake mechanism, and automatically operable means associated with saidbrake mechanism for taking up slack due to wear on the parts thereof,said last mentioned means including an electric motor for adjusting saidmechanism to take up said slack due to said wear, an electric circuitconnected to said motor, a control switch in said circuit, meansassociated with said operating means for retaining said control switchopen during normal operations of said actuating element betweenbrake-applying and brake-releasing position thereby interrupting thecircuit to said motor, and means operable by movement of said elementbeyond a predetermined brakeapplying position for closing said controlswitch when slack occurs in said brake mechanism to energize said motorfor operation to take up said slack and to return said element to itspredetermined brake-applying position, said control switch thereuponopening to deenergize said motor.

5. In a device of the class described, the combination of a frictionbrake mechanism, operating means for said brake mechanism, andautomatically operable means associated with said brake mechanism fortaking up slack due to wear on the parts thereof, said last mentionedmeans including a reversible electric motor, means forming a drivingconnection between said motor and the slack take-up means for operationof said take-up means by said motor, an electric circuit connected tosaid motor, a control switch in said circuit, means associated with saidoperating means for retaining said control switch open during normaloperation of said operating means thereby interrupting the circuit tosaid motor, means for closing said control switch when slack occurs insaid brake mechanism thereby closing the said circuit to said motor andcausing operation of said motor to take up said slack, and manuallyoperable reversing switch means in said 4 13 circuit for reversing theoperation of said electric motor.

6. In a device of the class described, the combination of a wheel brakemechanism comprising a pair of brake shoes, one of said brake shoesbeing disposed at each side of said wheel, a lever operatively connectedto each of said brake shoes, adjustable means connecting said levers forsimultaneous movement, operating means for actuating said levers to movesaid brake shoes into and out of engagement with said wheel, meanscarried by one of said levers for actuating said adjustable means totake up all excess slack in said brake mechanism as soon as it occurstherein, said last mentioned means including a reversible electricmotor, means forming a driving connection between said motor and saidadjustable means for varying the effective length of said adjustablemeans upon operation of said motor, an electric circuit connected tosaid motor, a control switch in said circuit, means associated with saidoperating means for normally retaining said control switch open therebyinterrupting the said circuit to said motor, means for closing saidcontrol switch when slack occurs in said brake mechanism thereby closingsaid circuit to said motor causing the latter to actuate said adjustablemeans to take up said slack, and manually operable reversing switchmeans in said circuit for reversing the operation of said motor to causethe latter to actuate said adjustable means and said letters to movesaid brake shoes away from said wheel.

7. In a device of the class described, the combination of a wheel brakemechanism comprising a pair of brake shoes, one of said brake shoesbeing disposed at each side of said wheel, a lever operatively connectedto each of said brake shoes, a pair of spaced adjustable meinbersconnecting said levers for substantially simultaneous movement, rackmeans on said adjustable members, operating means for actuating saidlevers for moving said brake shoes into and out of engagement with saidwheel, and means carried by one of said levers for actuating saidadjustable members to take up all eX- cess slack in said brake mechanismdue to wear on the parts thereof during application of said brakes, saidlast mentioned means comprising a shaft, a pair of spaced pinionssecured tc said l shaft meshing with the said rack means on saidadjustable members, an electric motor, and reduction gearing operativelyconnecting said electric motor and said shaft.

8. In a device of the class described, the combination of a wheel brakemechanism comprising a pair of brake shoes, one of said brake shoesbeing disposed at each side of said wheel, a lever operatively connectedto each of said brake shoes, a pair of space-d adjustable membersconnecting said levers for substantially simultaneous movement, rackmeans on said adjustable members, operating means for actuating saidlevers for moving said brake shoes into and out of engagement with saidwheel, and means carried by one of said levers for actuating saidadjustable members to take up all excess slack in said brake mechanismdue to wear on the parts thereof, said last mentioned means comprising ashaft, a pair of spaced pinions secured to said shaft meshing with thesaid rack means on said adjustable members, a reversible electric motor,reduction gearing operatively connecting said electric motor and saidshaft, an electric circuit connected to said motor, a control switch 14in said circuit, means 'associated with said operating means forretaining said control switch open during normal operations of saidoperating means thereby interrupting the circuit to said motor, Vmeansfor closing said control switch when slack occurs in said brakemechanism thereby closing said circuit to said motor causing the latterto actuate said adjustable members to take upA said slack, and manuallyoperable reversing switch means in said circuit for reversing theoperation of said motor to cause the latter to actuate said adjustablemembers and said levers to move said brake shoes away from said wheel.

9. In a device of the class described, the combination of a wheel brakemechanism consisting of a pair of brake shoes, one brake shoe beingprovided at each side of the wheel, a brake lever for each of said brakeshoes, one or more adjustable pull rods connecting said levers forsubstantially simultaneous movement thereof and operating means foractuating said levers to move said brake shoes toward and away from saidwheel, each ofy said pull rods comprising a pair of spaced,substantially parallel members having laterally aligned, longitudinallyeX- tending slots therein, a series of spaced pins mounted in saidparallel members forming a self-cleaning rack, a shaft rotatably mountedin one of said levers, the ends of said shaft extending through andbeing guided in said longitudinally extending slots, pinions secured tosaid shaft respectively meshing with each of said racks, an electricmotor, reduction gearing connecting said motor and said shaft, andautomatically operable switch means for energizing said motor whenexcess slack occurs in said brake mechanism to operate said pull rods totake up all such slack.

l0. In a railroad car brake system having a brake shoe, a power source,and a mechanical linkage interconnecting said shoe and said source, saidpower source being manually controllable to move said linkageselectively to apply and release said brake shoe with respect to a wheelof said car, the combination therewith of means including .a secondpower source mechanically connected to said linkageand arranged andadapted when actuated to take up slack in said linkage by varying therelative positions of parts thereof and said shoe when said shoe isfully applied to said wheel, and a control system for automaticallyactuating said second power source upon movement of an element of saidlinkage to and beyond a predetermined position in applying said brakeshoe to said wheel, said control system including a power-controllinguni-t having structure operable when said element is beyond saidpredetermined position to maintain said actuation, but only until saidsecond power source has taken up said slack to an extent suicient toreturn said element to said predetermined position whereby a givenmovement of said element by said first mentioned power source willresult in the same braking force regardless of the condition of wear ofsaid shoe.

1l. In a railroad car brake system having a brake shoe, a power source,and a mechanical linkage interconnecting said shoe and said source, saidpower source being manually controllable to move said linkageselectively to apply and release said brake shoe with respect to a wheelof said car, the combination therewith of means including an electricmotor mechanically con- 15 nected to said linkage and arranged andadapted when actuated to take up slack in said linkage by varying therelative positions of parts thereof and said shoe when said shoe isfully applied to said wheel, and a switch mechanism operable by movementof an element of said linkage to and beyond a predetermined position inapplying said brake shoe to said Wheel for actuating said electricmotor, said switch mechanism including provisions to maintain saidactuation only until said electric motor has taken up said slack to anextent suicient to return said element to said predetermined positionwhereby a given movement of said element by said power source willresult in the same braking force regardless of the condition of wear ofsaid shoe.

12. In a device of the class described, the combination of a wheel brakemechanism comprising a plurality of brake shoes, brake levers for saidbrake shoes, an adjustable pull rod connecting said levers forsubstantially simultaneous movement thereof, operating means foractuating said levers to move said brake shoes toward and away from saidwheel, certain of said pull rods comprising a pair of spaced,substantially parallel members having laterally aligned, longitudinallyextending slots therein,-a plurality of spaced pins mounted in saidparallel members forming a self-cleaning rack, a shaft rotatably mountedin one ofA said levers, the ends of said 30 shaft extending through andbeing guided in said longitudinally extending slots, a pinion secured tosaid shaft meshing with one of said racks, an actuator for said pinion,reduction gearing connecting said actuator and said shaft, and controlmeans for said actuator operable when slack occurs in said brakemechanism to adjust said pull rods to take up such slack.

THOMAS JAMES, J a.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 330,251 McLeod Nov. 10, 1885488,314 Hinckley Dec. 20, 1892 767,364 Rathbun et al Aug. 9, 1904.773,362 Anderson Oct. 25, 1904 834,107 Case Oct. 23, 1906 874,219Mahoney Dec. 17, 1907 1,609,459 Burnham Dec. 7, 1926 1,681,058 SauvageAug. 14, 1928 1,937,683 Boirault Dec. 5, 1933 1,947,675 Schwentler Feb.20, 1934 2,127,920 James Aug. 23, 1938 2,236,259 Cameron Mar. 25, 19412,236,263 Farmer Mar. 25, 1941 2,397,965 Hunz Apr. 9, 1946 FOREIGNPATENTS Number Country Date 25,129 Great Britain Dec. 22, 1904

